Process for protecting porous structure using nanoparticles driven by electrokinetic pulse

ABSTRACT

A process for protecting a porous structure includes providing a treatment fluid including nanoparticles including a sealant material coated with a metal ion to a face of the porous structure, and applying a sequence of DC voltage pulses to the porous structure in a position so as to drive the nanoparticles on the face of the porous structure into the porous structure. The metal ion coating of the nanoparticle separates from the sealant material within the porous structure to close pores within the porous structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 61/056,112 filed May 27, 2008, the entirety of which is herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention generally relates to processes for protectingporous structures such as concrete from deterioration, and moreparticularly to a process for moving particles into the porous structurethat can prevent and/or ameliorate deterioration of the porousstructure.

BACKGROUND OF THE INVENTION

Structures made of materials such as concrete, brick and othercementitious construction materials are porous and therefore subject toinvasion by water and other substances. Alkali silica reaction (ASR) isa degradation mechanism in cementitious materials caused by thecombination of reactive siliceous aggregates, sufficient alkali andwater. ASR forms a gel that expands, with addition of water, and damagesconcrete and mortars. In addition, reinforcing structure (e.g., rebar)within the concrete will degrade in the presence of water and othersubstances and causes further degradation of the overall structure.

SUMMARY OF THE INVENTION

In one aspect, a process for protecting a porous structure generallycomprises providing a treatment fluid including nanoparticles comprisinga sealant material coated with a metal ion to a face of the porousstructure. A sequence of DC voltage pulses is applied to the porousstructure in a position so as to drive the nanoparticles on the face ofthe porous structure into the porous structure. The metal ion coating ofthe nanoparticle separates from the sealant material within the porousstructure, and the sealant material is used in closing pores within theporous structure.

In another aspect, a process for moving nanoparticles into a concretestructure having capillary pores to treat the concrete structuregenerally comprises delivering a treatment fluid mixture ofnanoparticles within a carrier liquid to an anode. The nanoparticlescomprise silica colloidal nanoparticles coated with lithium. A sequenceof DC voltage pulses is applied to the anode to induce movement of thetreatment fluid mixture from the anode toward a cathode spaced remotelyfrom the anode so that the treatment fluid mixture flows into thecapillary pores of the concrete structure. Lithium ions of thenanoparticles separate from the silica colloidal nanoparticles in thecapillary pores of the concrete structure. The separated lithium ionsprevent or mitigate alkali-silica reactions (ASR) in the concretestructure and the silica colloidal nanoparticles react with free calciumhydroxides in the concrete structure to create calcium silicate hydrate(CSH).

In yet another aspect, a process for moving nanoparticles into aconcrete structure having capillary pores to treat the concretestructure generally comprises delivering a treatment fluid mixture ofnanoparticles within a carrier liquid to an anode. The nanoparticlescomprise a polymer coated with zinc. A first sequence of DC voltagepulses is applied to the anode to induce movement of the treatment fluidmixture from the anode toward a cathode spaced remotely from the anodeso that the treatment fluid mixture flows into the capillary pores ofthe concrete structure. A second sequence of DC voltage pulses isapplied to drive the carrier liquid out of the concrete structureleaving the polymer coated with zinc in the capillary pores, whereby thepolymer expands into pores within the concrete structure.

Other features will be in part apparent and in part pointed outhereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a first embodiment of an electrokinetic pulsedevice;

FIG. 2 is a schematic of a mesh anode of the electrokinetic pulse devicein FIG. 1 electrically connected to a power supply;

FIG. 3 is a schematic of a second embodiment of the electrokinetic pulsedevice;

FIG. 4 is a schematic of a third embodiment of the electrokinetic pulsedevice;

FIG. 5 is a schematic of a porous anode of the third embodiment of theelectrokinetic pulse device;

FIG. 6 is a schematic of a fourth embodiment of the electrokinetic pulsedevice; and

FIG. 7 is a graph showing the electrokinetic pulses provided to in aprocess according to the present invention.

Corresponding reference characters indicate corresponding partsthroughout the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the drawings, and in particular to FIG. 1, a firstembodiment of an electrokinetic pulse (EKP) device is generallyindicated at 10. As explained in more detail below, the EKP device 10 isconfigured to move a treatment fluid mixture of charged (negatively orpositively charged) nanoparticles within a carrier liquid through aporous structure 11, such as hardened concrete. Electrokinetic transportincludes ionic conduction, electrophoresis, and electroosmosis. Ionicsolution conductivity accounts for the overwhelming majority ofconductivity measured in concrete. In an aqueous system (concretestructures generally retain some level of moisture content), ions can beinduced to drift in response to an applied electronic field.Electrophoresis is characterized by the movement of a solid particledispersed in an electrolyte under the influence of an electric field.Electroosmosis is the induced flow of water through a porous medium whenan electric potential is applied across the medium.

Electro-osmosis has origins in 1809, when F. F. Reuss originallydescribed an experiment demonstrating that water could be forced to flowthrough a clay-water system when an external electric field was appliedto the soil. Research since then has shown that water surrounding thecations moves with them, the flow initiated by the movement of cationspresent in the pore fluid of a clay, or like porous media such asconcrete, brick, and other cementitious construction materials.

The EKP device 10 according to one embodiment of the present inventionincludes an anode applicator, generally indicated at 12, and fluiddelivery system, generally indicated at 14, for delivering the treatmentmixture to the anode applicator. In the first embodiment, the anodeapplicator 12 includes an applicator housing 16 and a porous anode 18received in the housing. The porous anode 18 may be of a generallyplanar, mesh construction, such as an expanded titanium mesh strip thatis coated with a mixed-metal oxide catalyst. A suitable mesh anode isavailable from Corrpro Companies Inc., of Medina, Ohio. Other types ofporous anodes do not depart from the scope of the present invention. Inuse, the anode 18 is positioned close to, but not in contact with theporous structure 11. In one embodiment, nonconductive spacers (notshown) may be used to locate the anode 18 relative to the porousstructure 11.

In the illustrated embodiment, the mesh anode 18 is located in adistensible member, generally indicated at 19. The distensible member 19includes a liquid impervious upper portion 20, such as a latex material,and a liquid pervious lower portion 22, such as a porous fabric orabsorbent spongy material. In the illustrated embodiment, thedistensible member 19 is generally cuboidal, where the upper portion 20includes an upper face and four side faces and the lower portion 22includes a bottom face. At least the upper portion 20 may be distendedto some degree under fluid pressure. As will be explained in more detailbelow, the applicator housing 16 includes an open bottom through whichthe bottom face of the lower portion 22 contacts a surface of the porousstructure to be treated. Generally, contact of the lower portion 22 withthe surface of the porous structure places treatment fluid mixture onthe face of the porous structure. However, the portion may be locatedclose to, but not in contact with the face of the porous structure andstill be considered to have treatment fluid mixture on the face of theporous structure. In one example, the distensible member 19 may have alength of about 4 ft (1.2 m), a depth of about 4 ft (1.2 m), and aheight of about 6 in (15.2 cm), and the mesh anode 18 may have a lengthof about 4 ft (1.2 m), a depth of about 4 ft (1.2 m. The anodeapplicator 12 may have other configurations without departing from thescope of the present invention. For example, a mesh anode may bedisposed between upper and lower absorbent layers so that opposite facesof the porous anode are in contact with the absorbent material.

The fluid delivery system 14 includes a treatment container 30 forholding a quantity of the treatment fluid mixture, and a pump 32 orother fluid mover for delivering the treatment fluid mixture from thetreatment container to inlet(s) 33 of the anode applicator 12. In oneexample, the treatment container 30 may be a large volume container, andthe pump 32 may be a pump that is suitable for delivering between about⅛ L/hour and about 5 L/hour of treatment fluid mixture to the anodeapplicator 12. The treatment container 30 and the pump 32 may have otherspecifications and working capabilities without departing from the scopeof the present invention. Flexible tubing 34 fluidly connects thetreatment container 30 to the pump 32, and additional flexible tubing 35connects the pump to the anode applicator 12. The components may befluidly connected in other ways without departing from the scope of thepresent invention. Moreover, the treatment fluid mixture may bedelivered to the anode applicator 12 in other ways without departingfrom the scope of the present invention.

Referring to FIGS. 1 and 2, the EKP device 10 also includes a powersupply 36 that is electrically connected to a cathode 38 and the meshanode 18 by independent electrical lead wires 39 or in other wayswithout departing from the scope of the present invention. The powersupply 36 may be a DC or AC generator, whose output signal (e.g.,voltage) is controlled by a controller 40, such as a microcontroller. Inthe illustrated embodiment (FIG. 2), separate lead wires 39 areconnected at a center and four corners of the mesh anode 18. Thecontroller 40 controls the power supply 36 to apply equal amounts ofcurrent to each of the five connection points of the mesh anode 18 sothat current is uniformly distributed across the face of the anodeduring active treatment. In one example, which is explained in moredetail below, the output signal from the power supply 36 may be a pulsedDC signal (e.g., voltage signage). An exemplary sequence of DC voltagepulses is illustrated in FIG. 7. In this illustrated sequence, apositive pulsed DC voltage of a selected magnitude (e.g., within a rangeof about 30 volts to about 50 volts) is applied for 100 ms, followed by0 volts for 100 ms. In the illustrated embodiment, this 100 ms ofpositive DC voltage followed by 0 volts is repeated 9 more times for atotal of 10 times. After the 10th time (an elapsed time of 2 seconds), anegative pulsed DC voltage of a selected magnitude (e.g., within a rangeof about −30 volts to about −50 volts) is applied, followed by 0 voltsfor 100 ms. Applying a negative pulsed DC voltage every 2 seconds or soprevents polarization of the cathode and anode. The illustrated sequenceis repeated for up to 48 to 72 hours or more, depending on the treatmentand the structure being treated.

In one example, the parameters of the output signal may be selectable bythe user and implemented by the controller 40. For example, the user maybe able to select the most effective voltage, amperage, pulse sequence,pulse duration, pulse shape and treatment period for a givenapplication. In one embodiment, the duration of the electrokineticpulses may be from about 10 ms to about 100,000 ms and the voltage rangemay be from about 20V to about 100V. The controller may also beconfigured (i.e., programmed) to automatically switch the direction ofthe flow of electrical current from the cathode 38 to porous anode 18 toreduce polarization of the cathode and anode. Further, the controllermay be configured (i.e., programmed) to provide the user withprogrammable controls over the quantity, timing and duration of themixture delivered to the anode applicator platform.

The ability to control such parameters gives the user flexibility inapplying treatments from structure to structure. For example, one maywant to use a higher voltage in order to move nanoparticles into theporous structure more quickly. The greater magnitude of the voltage, thegreater the particle density, but the more concrete damage is likely.Also, for example, changing pulse duration from a typical 1 to 6 secondseach, to only 100 milliseconds each will drive the nanoparticles deeperbecause the faster the pulses, the greater the depth penetration ofnanoparticles. Moreover, different durations of negative pulses(reversed polarity—anodes become cathodes, cathodes become anodes) totry to get more positive pulses sandwiched in between two negativepulses may be advantageous in some applications because it is believedthat increasing the total percentage of positive vs. negative pulses inone sequence will increase the amount of nanoparticles that can bemigrated into the porous structure. However, it is also believed thatthe lower the percentage of negative pulses in a repeating sequence, thegreater risk of polarizing the electrodes (anodes and cathodes).

Referring to FIG. 4, a second embodiment of an anode of the EKP device10 is generally indicated 118. The anode 118 comprises at least oneporous anode tube in place of the porous anode 18 and absorbent layers22, 24. The porous anode tube(s) 118 may be embedded in the porousstructure 11. The porous anode tube 118 is in fluid communication withthe fluid delivery system 14 for receiving the treatment fluid mixturefrom the container 30. The anode tube 118 may include a plurality ofopenings 120 to allow movement of the treatment mixture out of the tubeand toward the cathode during treatment.

In the embodiment illustrated in FIGS. 1 and 4, the cathode 38 comprisesa metal object or an interconnected series of metal objects that areinserted into the porous structure 11 to be treated. For example,hole(s) may be drilled into the porous structure 11 and the cathode(s)38 may be inserted therein. In another example (FIG. 3), a metalreinforcement component 42 (e.g., steel rebar) embedded in the porousstructure may be used as the cathode. Referring to FIGS. 5 and 6, in yetanother example, the cathode 38 may comprise one or more metalsaturation tubes 44 inserted into soil S (i.e., earth) adjacent theporous structure 11. The saturation tube 44 includes openings 45 or areotherwise porous for delivering fluid outward into the soil. Forexample, the saturation tubes 44 may be made from copper, and may have adiameter of between 0.5 in and 1.0 in. In this illustrated embodiment(FIGS. 5 and 6), flexible tubing 46 fluidly connects the metalsaturation tube(s) 44 to a container 48 comprising an electricallyconductive fluid (e.g., an electrolyte solution). A pump 50 delivers theelectrically conductive fluid into the metal saturation tube(s). Thedelivered fluid flows through the openings 45 in the metal saturationtube(s) 44 and saturates the area surrounding the metal saturation tube.The saturated area effectively becomes cathodic to increase the size,uniformity and coverage of the cathode surface area so as to provide aneffective ratio of cathode surface area to anode surface area. Thecathode(s) 38 may be of other types and configurations without departingfrom the scope of the present invention. In general, the cathode(s) 38would be placed on the opposite side of the porous structure 11 (fromthe anode 18). The cathode 38 may be in direct contact with the porousstructure (e.g., embedded in the porous structure) or may be next to theporous structure in a porous media. As one example, if the porousstructure is reinforced with steel, the reinforcing structure may beused as the cathode. Preferably, the cathode 38 is wet with water orcompatible electrolyte solution to maintain uniform cathodic polarity onthe opposite side of the anode 18.

In the embodiment of FIGS. 5 and 6, the porous structure 11 has avertical orientation. Thus, the applicator housings 16 are particularlyconfigured to prevent escape of the treatment fluid mixture down theface of the structure. For example a nonconductive seal or dam is placedat the circumference of the housing to retain the treatment fluidmixture.

In one embodiment (FIG. 3), circuitry minimizes stray current corrosionof steel reinforcement 42 (e.g., rebar) and metal penetrations duringactive treatments. This circuitry divides the negative potential betweenthe protected steel and the cathode by means of real-time feedback fromembedded half-cells. Programmed power supply circuitry provides anelectrical path for stray current on steel reinforcement to return tothe power supply. If the corrosion potential of the steel reinforcementincreases during the treatment, the controller may be programmed toprovide additional cathodic protection (negative potential) to thereinforcement.

Using any one of the embodiments described above or other embodiments,in use the EKP device 10 induces, by electro-osmosis, movement of thetreatment fluid mixture from the porous anode 18 toward the cathode 38.The anode applicator 12 is placed on the surface of the porous structureto be treated so that the anode 18 is generally opposing the surface andthe lower absorbent layer 22, through the open bottom of the applicatorhousing 16, is in contact with the surface. The treatment fluid mixtureis delivered to the anode 18 and the controller 40 supplies the anodewith a selected output signal from the power supply 38 so that thetreatment fluid mixture travels through capillaries and pores in thesurface of the porous structure and into the porous structure toward thecathode 38.

In one example (FIG. 6), a plurality of EKP device 10 may beinterconnected to concurrently treat large areas of a single porousstructure such as roadways, bridge decks, and sea walls. For example,the EKP device 10 may be mobile including, but not limited to, rollingapplicators similar to flat-bed trailers. In one embodiment, the EKPdevices 10 may be synchronized so that all anode applicators and tubesinvolved in a multi-applicator treatment of a single structure aresynchronized.

There are numerous treatments that can be applied to the porousstructure 11 using the EKP device 10, 110. In one example, the treatmentfluid mixture may comprise coated nanoparticles in a carrier liquid. Thecoated nanoparticles in the carrier liquid are moved into and throughthe porous structure using a pulsed-DC output signal (i.e., pulsed DCvoltage) from the power supply 38. In one exemplary treatment, thecoated nanoparticles may comprise nanoparticles of silicate coated withlithium (i.e., lithium-coated silicate) mono-dispersed in water. Forexample, the lithium-coated silicate may be amorphous, silica colloidalnanoparticles that are encapsulated with lithium that is held on thesurface of the silica by an ionic bond. The treatment mixture mayinclude lithium-coated silicate nanoparticles of differing sizes. Forexample, the nanoparticles may have diameters ranging from about 10 nmto 100 nm, and more preferably from about 30 nm to about 60 nm. It willbe understood that the appropriate sizes will depend upon the nature ofthe porous material and in particular the size of the pores in thatmaterial. Moreover, different sized particles may be used in the sametreatment fluid mixture. Smaller sizes may more completely fill pores,but larger sizes will complete the job more rapidly. In one example amixture of 30 nm and 60 nm particles may be used in the treatment fluidmixture.

The sequence of pulsed DC voltages illustrated in FIG. 7 and describedabove may be utilized in this example to drive the lithium-coatedsilicate into the porous structure 11. As the lithium-coated silicateare being driven into the porous structure 11, it is believed thatlithium ions (broadly, “metal ions”) separate from the silicateparticles, whereupon the lithium ions prevent or mitigate ASR gelexpansions in the concrete and the silicate (broadly, “a sealantmaterial”) reacts with free calcium hydroxides to create precipitatesincluding calcium silicate hydrate (CSH), which fills the pores andcapillaries, and helps prevent chlorides from reentering the treatedarea. It is also believed that the distribution of the lithium-coatedsilicate nanoparticles within hardened concrete, or other porousstructure, will prevent or mitigate rebar corrosion and sulphate attackin the concrete.

In another exemplary treatment, the coated nanoparticles in the carrierliquid may comprise coated latex nanoparticles, such as zinc-coatedlatex nanoparticles, mono-dispersed in water. The latex may be morebroadly considered a polymer and still more generally a “sealantmaterial.” For example, the zinc-coated latex nanoparticles may be latexcolloidal nanoparticles encapsulated with zinc that is held on thesurface of the colloidal nanoparticles by an ionic bond. The treatmentmixture may include zinc-coated latex nanoparticles of differing sizes.For example, the nanoparticles may have diameters ranging from about 30nm to about 60 nm

In a first step of this treatment using zinc-coated latex nanoparticles,the porous structure 11 is dehydrated using the EKP device 10. A firstsequence of pulsed-DC electrical signals (e.g., voltages) is applied todrive water is driven out of structure 11 by electro-osmosis. The firstsequence of pulsed-DC electrical signals may be a conventional sequenceas known in the art. After dehydrating the porous structure 11, thezinc-coated latex particles are moved into the hardened concrete, orother porous structure, using a second sequence of pulsed-DC electricalsignals (e.g., voltages) from the power supply 38, as controlled by thecontroller 40, to create a second pulsating electrokinetic field betweenthe anode 18 and the cathode 38. The sequence of pulsed DC voltagesillustrated in FIG. 7 and described above may be utilized in thisexample to drive the coated latex particles into the porous structure11.

Typically, although not necessarily, there is a delay following drivingthe zinc-coated latex nanoparticles into the hardened concrete.Subsequently, a second dehydration step by electroosmosis is carriedout. The operation may be substantially the same as the firstelectroosmosis step. The second electroosmosis step drives water out ofthe latex causing the polymer in the latex to self assemble. In otherwords the polymer expands out in tendrils into pores in the hardenedconcrete, thereby sealing the pores.

The treatments may last anywhere from several hours to several monthsdepending on the concentration and depth of penetration of the treatmentfluid mixture desired. In the case of lithium coated silicates, once theelectrokinetic field is removed, the lithium is allowed to react withthe ASR gel to prevent gel expansion. The silicate particles will thenreact with the free calcium hydroxide and form calcium silicate hydratecompounds that densify and strengthen concrete while also effectivelyreducing the available alkali in the cementitious matrix. In the case ofzinc-coated latex nanoparticles, zinc separates from the latex insidethe porous structure and plates on any steel (e.g., rebar) in the porousstructure. This protects the steel against corrosion. The latex free ofits zinc coating is operable to close pores within the porous material.

With any of the above treatments or other treatments using the EKPdevice, probe sensors can be used to provide real-time feedback to thepower supply indicating the ratio of lithium to potassium and sodium,the ratio of hydroxyl ions to chloride ions, and permeability changes.After the desired ratios are achieved, the user is notifiedautomatically by an electronic display connected to the power supplythat treatment for that particular area is successful. The electrodesare removed from the structure, and repairs are made to any anode and/orcathode holes.

Moreover, in one embodiment the EKP device may include a system forself-monitoring (i) the ratio of lithium to potassium and sodium ions soas to determine effectiveness of the alkali-silica reaction (“ASR”)treatment, (ii) the ratio of chloride to hydroxyl ions so as todetermine the effectiveness of the corrosion treatment, and (iii) themoisture transmission rates within the concrete or other material so asto determine the effectiveness of the permeability reduction treatment,and (iv) the uniformity of current distribution across the face of eachanode or cathode applicator, so as to determine the effectiveness ofeach applicator for its intended use.

Moreover, during treatment sufficient quantities of conductive fluidsmay be introduced into the surrounding permeable media, saturating saidmedia with those fluids, embedding cathode in said saturated media, andusing said saturated media as a wide-coverage cathode similar in size tothe surface area of the anode to ensure that the coated particles and/orlatex spheres are distributed throughout the treated structure.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the” and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions, products,and methods without departing from the scope of the invention, it isintended that all matter contained in the above description and shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

1. A process for protecting a porous structure comprising: providing atreatment fluid including nanoparticles comprising a sealant materialcoated with a metal ion to a face of the porous structure; applying asequence of DC voltage pulses to the porous structure in a position soas to drive the nanoparticles on the face of the porous structure intothe porous structure; wherein the metal ion coating of the nanoparticleseparates from the sealant material within the porous structure, thesealant material being for use in closing pores within the porousstructure.
 2. A process as set forth in claim 1 wherein applying asequence of DC voltage pulses comprises applying pulses having aduration of less than about 1000 ms.
 3. A process as set forth in claim2 wherein the pulse duration is about 100 ms.
 4. A process as set forthin claim 2 wherein the pulses are separated from each other by an timeapproximately equal to the duration of the pulse.
 5. A process as setforth in claim 1 wherein applying a sequence of DC pulses comprisesperiodically changing the polarity of the DC pulse.
 6. A process as setforth in claim 5 wherein periodically changing the polarity compriseschanging the polarity of no more than about 1 out of every 5 DC voltagepulses applied to the porous structure.
 7. A process as set forth inclaim 5 wherein periodically changing the polarity comprises changingthe polarity of no more than about 1 out of every 10 DC voltage pulsesapplied to the porous structure.
 8. A process as set forth in claim 1wherein providing a treatment fluid comprises providing nanoparticleshaving a silicate sealant material.
 9. A process as set forth in claim 8wherein providing a treatment fluid comprises providing nanoparticleshaving a lithium ion coating.
 10. A process as set forth in claim 9wherein providing a treatment fluid comprises providing nanoparticleshaving a latex sealant material.
 11. A process as set forth in claim 10wherein providing a treatment fluid comprises providing nanoparticleshaving a zinc ion coating.
 12. A process as set forth in claim 10further comprising, subsequent to said step of applying a sequence of DCpulses of applying electroosmosis to the porous structure to dehydratethe latex and initiate self assembly of the latex to block pores withinthe porous structure.
 13. A process for moving nanoparticles into aconcrete structure having capillary pores to treat the concretestructure, the process comprising: delivering a treatment fluid mixtureof nanoparticles within a carrier liquid to an anode, the nanoparticlescomprising silica colloidal nanoparticles coated with lithium; applyinga sequence of DC voltage pulses to the anode to induce movement of thetreatment fluid mixture from the anode toward a cathode spaced remotelyfrom the anode so that the treatment fluid mixture flows into thecapillary pores of the concrete structure, wherein lithium ions of thenanoparticles separate from the silica colloidal nanoparticles in thecapillary pores of the concrete structure, wherein the separated lithiumions prevent or mitigate alkali-silica reactions (ASR) in the concretestructure and the silica colloidal nanoparticles react with free calciumhydroxides in the concrete structure to create calcium silicate hydrate(CSH).
 14. A process for moving nanoparticles into a concrete structurehaving capillary pores to treat the concrete structure, the processcomprising: delivering a treatment fluid mixture of nanoparticles withina carrier liquid to an anode, the nanoparticles comprising a polymercoated with zinc; applying a first sequence of DC voltage pulses to theanode to induce movement of the treatment fluid mixture from the anodetoward a cathode spaced remotely from the anode so that the treatmentfluid mixture flows into the capillary pores of the concrete structure,applying a second sequence of DC voltage pulses to drive the carrierliquid out of the concrete structure leaving the polymer coated withzinc in the capillary pores, whereby the polymer expands into poreswithin the concrete structure.